1. Field of the Invention
The present invention relates to the field of wireless communication. More particularly, the present invention relates to handling in-device co-existence interference in a user equipment.
2. Description of the Related Art
Coexistence of Long Term Evolution (LTE) with Industrial, Scientific and Medical (ISM) (Bluetooth®, Wi-Fi®, and the like) band technologies and Global Navigation Satellite Systems (GNSS) is necessary as these are becoming very common combinations in User Equipments (UEs) such as cell phones. However, each of these technologies is developed by different groups to serve a specific purpose and thus the characteristics of each of these technologies are different. For example, they operate in different frequencies, have different access mechanisms, have different frame structures, have different peak transmit powers, and the like.
When all of these technologies operate simultaneously in an adjacent band (small separation e.g., <20 MHz), usually 50 decibel (dB) isolation is required. However, the small form factor of the UE provides only 10-30 dB isolation. As a result, the transmitter of one radio severely affects the receiver of another radio. For example, the small form factor of the UE may pose a great challenge of interference from transmission of ISM technology to the receiver of cellular technologies such as LTE or Worldwide Interoperability for Microwave Access (WiMax®). Similarly, the transmitter of cellular technology may cause severe interference to the ISM receiver. The main cause of in-device co-existence issues may be because of receiver blocking due to limited dynamic range of a power amplifier, an Analogue to Digital converter and out of band emission due to imperfect filtering.
LTE Coexistence with Bluetooth®
FIG. 1A is a schematic diagram illustrating separation between LTE and Bluetooth® channels according to the related art.
Referring to FIG. 1A, an LTE band 7 UpLink (UL) and Bluetooth® band are separated by 20 MHz. The band 7 is a Frequency Division Duplexing (FDD) band and hence the LTE receiver is not affected by the Bluetooth® transmitter. However, the LTE transmitter can affect the Bluetooth® receiver. Also, there is very negligible separation of 2 MHz between LTE band 40 (Time Division Duplexing (TDD) band) and the Bluetooth® frequency band. Therefore, it is not possible to discontinue using the higher portion of LTE band 40 in case of coexistence.
LTE Co-Existence with Wireless Fidelity (Wi-Fi®)
FIG. 1B is a schematic diagram illustrating separation between LTE and Wi-Fi® channels according to the related art.
Referring to FIG. 1B, there are 14 channels demarcated in an ISM band for a Wi-Fi® operation. Each channel is separated from another channel by 5 MHz with an exception of channel number 14 which is separated by 12 MHz. The first channel (i.e., channel 1) starts with 2401 MHz and hence there is almost no separation between LTE band 40 and Wi-Fi®. Channel 14 of Wi-Fi® ends at 2495 MHz so, theoretically, only 5 MHz separation is available between the LTE band 7 and the Wi-Fi®. Different countries have different policies for the number of allowed channels of Wi-Fi®. Currently, many countries allow only channels 1 to 13 whereas Japan allows usage of channel number 14 only for IEEE 802.11b based communication. This suggests that, even though in theory only 5 MHz separation is available between the Wi-Fi® and the LTE band 7, in practice at least 17 MHz is available.
Generally, in the Time Division Multiplexing (TDM) domain, a scheduling gap pattern is communicated between an evolved Node B (eNB) and a UE. The scheduling gap pattern consists of an active time period (e.g., an LTE ON period) and an inactive time period (e.g., an LTE OFF period). The scheduling gap pattern is communicated to the UE as Discontinuous Reception (DRX) cycle parameters or a bitmap, reduced Hybrid Automatic Repeat Request (HARQ) processes, and measurement gaps. Typically, an LTE module in a UE is configured to perform data transmission during the active time period indicated in the scheduling pattern so that an ISM module can operate during the inactive time period of the LTE module. Also, the eNB does not schedule DownLink (DL) data transmission to the UE during the inactive time period. This helps resolve in-device co-existence interference between the LTE module and the ISM module. Normally, the UE may perform other uplink LTE activities along with data transmission such as random access channel transmission, scheduling request transmission, channel quality indication report transmission, HARQ ACKnowledgment/Not-ACKnowledgment (ACK/NACK) transmission, Sounding Reference Signals (SRS) transmission, and the like. These LTE activities/procedures may coincide with the inactive time period reserved for the inference free operation of the ISM module, thereby causing interference to the ISM module operation.
Accordingly, there is a need for an improved method and apparatus for handling in-device co-existence interference in a user equipment.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present invention.